Normative Signs: The Poetry of "Ought"

This was on a narrow and crowded sidewalk on Yonge Street in Toronto. There were, indeed, men (or rather one man) working overhead. (So the gendered language was accurate — this time.)

What am I actually supposed to do, faced with this sign? What does exercising caution look like here? Does it merely mean, say, not loitering on the spot, in order to minimize the chance that something might fall on my head? If that’s a real risk, then it’s a real risk to the hundreds of people who each spent a second or two walking through.